JP2019177346A - Cleaning method of sprinkling filter bed - Google Patents

Abstract

To provide a cleaning method of a sprinkling filter bed, capable of suppressing the occurrence of filter bed fly larvae and scallops from a sprinkling filter bed and effectively recovering the water treatment capacity of the sprinkling filter bed.SOLUTION: The present invention provides a cleaning method of a sprinkling filter bed having a filter-medium layer which consists of a plurality of filter media in a water tank. Such a cleaning method includes a measurement process for measuring the amount of biofouling (Bm) to the filter medium, and a cleaning process for cleaning the filter medium. In this cleaning step, when the amount of biofouling (Bm) is greater than a predetermined cleaning selected biofouling amount (Bw), the filter medium is agitated and cleaned, and when the amount of biofouling (Bm) is smaller than or equal to the predetermined cleaning selected biofouling amount, the filter medium is immersed and cleaned.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a watering filter bed cleaning method.

  Conventionally, in a water treatment system, water to be treated is sprayed on a filter medium layer made of a filter medium carrying microorganisms, and a watering filter that aerobically biotreats organic matter in the water to be treated by microorganisms present in the filter medium layer. Floor is used.

  Here, if the water to be treated is continuously treated in the sprinkling filter bed, the biofilm attached to the filter medium becomes excessively thick, and the thickened sludge-like biofilm forms voids between the filter media. There was a possibility that the water treatment function of the sprinkling filter bed might be reduced due to the blockage. In addition, in the sprinkling filter bed, filter beds and scallops grow in the sprinkling filter bed and eat these biofilms formed on the filter medium surface, resulting in the water treatment function of the sprinkling filter bed. There was a risk of lowering. For this reason, in a water treatment system using a trickling filter, in order to continuously carry out efficient treatment of the treated water, the filter media layer is washed at an appropriate time, and an excessively thick biofilm or sludge is formed. It is necessary to remove eggs, larvae of moths, shellfish and eggs thereof from the filter bed.

  Conventionally, the filter medium constituting the filter medium layer was agitated and washed at a predetermined timing and adhered to the solid matter trapped in the filter medium layer and the filter medium for the problem of generation of malodor and filter bed soot in the sprinkling filter bed. There has been proposed a method for suppressing the generation of malodor and filter bed by removing the eggs and larvae of the filter bed from the filter medium layer (see, for example, Patent Document 1). In Patent Document 1, when the water treatment capacity is reduced to a predetermined threshold value or less and / or by stirring and washing the filter medium constituting the filter medium layer every predetermined time, bad smell and filter bed cake from the filter medium layer The idea of suppressing the occurrence of this is disclosed.

International Publication No. 2012/161339

  The above-mentioned Patent Document 1 does not disclose the details of the timing of performing the agitation cleaning in the case where the water treatment capacity is reduced below a predetermined threshold and / or every predetermined time. Therefore, the method disclosed in Patent Document 1 has room for improvement in terms of further optimizing the timing for performing stirring and cleaning of the filter medium. Here, if the filter medium is agitated and washed at a timing when the filter medium should not be agitated and washed, there is a risk that the water treatment capacity of the sprinkling filter bed may be reduced. Therefore, by washing the filter medium with an appropriate method according to the condition of the filter medium (for example, the amount of living organisms), the generation of larvae and scallops from the filter bed is suppressed, and the water filter There has been a need to establish a watering filter bed cleaning method that can effectively restore the water treatment capacity of the floor.

  The present inventors have intensively studied to achieve the above object. The inventors of the present invention paid attention to the method of “immersion cleaning” in addition to “stir cleaning” as a method of cleaning the filter medium layer. Here, stirring washing is a method in which the filter medium is made to flow by stirring after the watering filter bed is full, and then drained. According to the agitation washing, the porosity of the filter medium packed bed can be recovered, the water treatment efficiency of the water to be treated can be stabilized, and the larvae and scallops of the filter bed can be controlled. On the other hand, the immersion cleaning is a method in which the watering filter bed is filled with water and the filter medium is immersed for a certain time and then drained. According to the immersion cleaning, it is possible to control the larvae and scallop shells of the filter bed while suppressing the decrease of the biofilm formed on the surface of the filter medium.

  As described above, “immersion cleaning” and “stir cleaning” have different characteristics, and if a suitable method can be selected in consideration of the state of the filter medium layer, water treatment with a sprinkling filter bed is possible. It is thought that efficiency can be further increased. Therefore, the present inventors appropriately switch the type of cleaning to be performed between immersion cleaning and stirring cleaning based on the state of the filter medium layer, so that the larvae and sakamaki of the filter bed from the watering filter bed can be obtained. The present invention has been completed by newly finding that the generation of shellfish and the like can be suppressed and the water treatment capacity of the water trickling filter can be effectively recovered.

  That is, this invention aims at solving the said subject advantageously, The washing | cleaning method of the trickling filter of this invention wash | cleans the trickling filter which has the filter-medium layer which consists of several filter media in a water tank. A method comprising: a measuring step for measuring a biological adhesion amount (Bm) to the filter medium; and a cleaning step for cleaning the filter medium, wherein the biological adhesion amount (Bm) is a predetermined cleaning in the cleaning step. The filter medium is stirred and washed when the selected biological attachment amount (Bw) exceeds, and the filter medium is immersed and washed when the biological attachment amount (Bm) is equal to or less than the washing selected biological attachment amount (Bw). Features. In this way, the amount of biological attachment (Bm) to the filter medium is measured in the measurement step, and the cleaning method to be performed in the cleaning step based on the value of the amount of biological attachment (Bm) is either immersion cleaning or stirring cleaning. By appropriately selecting whether or not, it is possible to suppress the generation of larvae and scallop shells from the sprinkling filter bed and to effectively restore the water treatment ability of the sprinkling filter bed.

  Here, in the watering filter bed cleaning method of the present invention, when measuring the biological adhesion amount (Bm) in the measurement step, the porosity (VRo) of the filter medium layer is measured, and a predetermined porosity setting value is obtained. It is preferable to obtain a difference from (VRi). By measuring the amount of biofouling based on the porosity in the filter medium layer, the amount of biofouling on the filter medium can be measured easily and with high accuracy.

  Furthermore, in the watering filter bed cleaning method of the present invention, in the measurement step, the porosity (VRo) is accumulated in a predetermined section of the filter medium layer when a cleaning liquid is caused to flow into the filter medium layer. It is preferable to measure based on the amount of inflow water. In measuring the porosity, by using the accumulated inflow amount of the washing water, it is possible to more easily and accurately measure the amount of biofouling on the filter medium.

  Furthermore, in the watering filter bed cleaning method of the present invention, the predetermined section of the filter medium layer is H / 40 or more and H / 10 or less from the lower end surface of the filter medium layer when the height of the filter medium layer is H. It is divided by one measurement start height (Hs) included in the height range and one measurement end height (He) included in the range from H / 40 to H / 10 from the upper end surface of the filter medium layer. It is preferred that By setting the section for calculating the accumulated inflowing water amount to a predetermined section excluding the vicinity of the lower end surface and the vicinity of the upper end surface of the filter medium layer, the amount of biological adhesion to the filter medium can be measured with higher accuracy.

  Further, in the watering filter bed cleaning method of the present invention, in the cleaning step, when the biofouling amount (Bm) exceeds the cleaning selected biofouling amount (Bw), It is preferable to include adjusting the cleaning strength in the stirring cleaning based on the difference (Bd = Bm−Bw). Based on the difference (Bd) between the biofouling amount (Bm) and the washing selected biofouling amount (Bw), by adjusting the washing strength at the time of stirring and washing, the larvae and Sakamaki of the filter bed from the watering filter bed The generation of shellfish can be more effectively suppressed, and the water treatment capacity of the trickling filter can be recovered more effectively.

  According to the present invention, the filter medium is washed by an appropriate method in accordance with the amount of biofouling on the filter medium, thereby suppressing the generation of larvae and scallops from the sprinkling filter bed, and the watering filter bed. Can effectively restore the water treatment capacity.

It is explanatory drawing which shows schematic structure of an example of the trickling filter which can apply the washing method of the typical trickling filter according to this invention. It is a perspective view of the filter medium which forms the filter medium layer in the sprinkling filter bed shown in FIG. It is explanatory drawing in the case of measuring the cumulative inflow water quantity to the predetermined area of a filter medium layer in the measurement process of the washing method of the typical sprinkling filter bed according to this invention. It is explanatory drawing which shows the state which is stirring and washing the water trickling filter according to the washing | cleaning method of the typical water trickling filter according to this invention. It is a graph which shows the relationship between the amount of biological adhesion to a filter medium, and soluble BOD removal amount. It is a graph which shows the relationship between the amount of biological adhesion to a filter medium, and ammonia nitrogen removal amount. It is a figure for demonstrating the case where the washing | cleaning method is switched in the washing | cleaning process of the washing method of the typical sprinkling filter bed according to this invention. It is a figure which shows the relationship between Bm, Bw, and Bd together with the relationship between the biological adhesion rate demonstrated in FIG. 5, and soluble BOD removal amount.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in each figure, what attached | subjected the same code | symbol shall show the same component.

(Washing filter floor cleaning method)
The washing method for the trickling filter of the present invention is not particularly limited, and can be used when washing the trickling filter used for the treatment of treated water such as sewage. And the washing method of the trickling filter bed of the present invention includes the measurement process of measuring the amount of biological adhesion (Bm) to the filter medium, and the cleaning process of cleaning the filter medium. Furthermore, in the washing method of the trickling filter of the present invention, when the biofouling amount (Bm) exceeds a predetermined washing selected biofouling amount (Bw) in the washing step, the filter medium is stirred and washed, and the biofouling amount ( The filter medium is immersed and washed when Bm) is equal to or less than the washing selected biological adhesion amount (Bw).

<Watering filter floor>
Here, the watering filter bed cleaned using the watering filter cleaning method of the present invention has a configuration as shown in FIG. Specifically, the trickling filter bed 100 shown in FIG. 1 includes a screen 20 and a filter medium layer composed of a screen 20 and a plurality of filter media 31 supported by the screen 20 and filled up to the height of the upper end face 32 of the filter medium layer. 30, an aeration apparatus 40 that feeds air to the filter medium layer 30, and a sprinkler 50 that is installed above the filter medium layer 30 and sprays water to be treated onto the filter medium layer 30. And the to-be-processed water piping 53 which has the flowmeter 51 and the to-be-processed water valve 52 is connected to the sprinkler 50. FIG. Further, the water tank 10 of the water trickling filter 100 has an outlet provided below the screen 20. A pipe 60 having a valve 61 is connected to the outlet. Although not shown, the pipe 60 may be branched into a treated water pipe and a washing water pipe via a three-way valve or the like on the downstream side of the illustrated area. Further, the water tank 10 has an opening at the connecting portion, and when water is accumulated in the water tank 10, a connecting pipe 70 that can indicate the water level, and a water level meter 71 attached to the connecting pipe 70. It has.

  Here, the water tank 10 is not particularly limited, and known water tanks such as a steel tank, a resin water tank, and a concrete water tank can be used. In addition, the shape of a water tank can be made into arbitrary shapes, such as a rectangular shape and a column shape.

  The filter medium layer 30 is composed of a plurality of filter media 31 filled in the water tank 10. Specifically, the filter medium layer 30 has a plurality of filter media 31 placed on the screen 20 installed on the beam 22 supported by a column 21 having one end fixed to the bottom surface of the water tank 10. It is filled up to this point. Here, the height of the filter medium layer upper end surface 32 is the filling height of the filter medium 31, and is usually about 1 to 4 m, preferably about 2.0 to 2.5 m. The mesh of the screen 20 is set to a size that the filter medium 31 does not pass through. Here, in the watering filter bed 100, a cylindrical resin filter material as shown in FIG. 2 was used as the filter medium 31, but in the watering filter bed of the present invention, the material and shape of the filter medium are arbitrary materials and shapes. It can be. For example, the material of the filter medium 31 is not particularly limited, and examples thereof include resins such as polypropylene and polyethylene. Further, for example, the shape of the filter medium includes a bowl shape and a hollow sphere shape in addition to the cylindrical shape.

However, since the plurality of filter media 31 constituting the filter media layer 30 can be dipped and washed, the average specific gravity needs to be more than 1.0 at the time of performing the washing step. Since the specific gravity of the filter medium 31 varies depending on, for example, the mass of the biofilm attached to the filter medium, the filter medium layer 30 is formed even if the average specific gravity before the biofilm is attached is less than 1.0. It can be used as a filter medium 31 for doing so. In addition, it is preferable that the average specific gravity of the filter medium 31 is more than 1 and 1.15 or less from the viewpoints of easy immersion and easy flow.
In the present specification, the average specific gravity of the filter medium 31 means a number average value when mass (g) / volume (cm ³ ) is calculated for 100 filter media.

  The aeration apparatus 40 functions to stir the filter medium 31 in the washing water when the filter medium 31 constituting the filter medium layer 30 is stirred and washed. The aeration apparatus 40 is connected to the blower 80 via a stirring air pipe 81. The blower 80 can be controlled by the monitoring control device 90.

  The sprinkler 50 functions as a to-be-processed water supply mechanism which sprays to-be-processed water on the filter medium layer 30 at the time of processing of to-be-processed water. The water sprinkler 50 functions as a cleaning liquid storage mechanism that stores the water to be treated as the cleaning liquid in the water tank 10 together with the valve 61 provided in the pipe 60 when the water trickling filter 100 is cleaned.

The flow meter 51 constantly measures the flow rate of the water to be treated, and transmits the measured value to the monitoring control device 90 every predetermined time (for example, 1 minute).
In this example, the water to be treated as the cleaning liquid can be stored using the water sprinkler 50. However, the watering filter bed 100 is provided with cleaning water other than the water to be treated (for example, reclaimed water, middle water, river water, water supply). You may provide the piping which passes the flowmeter 51 and supplies water, industrial water, a chemical | medical solution, etc.) into the water tank.

  And in the trickling filter bed 100, as it demonstrates in detail below, the process of to-be-processed water and the washing | cleaning of the filter medium 31 which comprises the filter medium layer 30 of the trickling filter bed 100 can be performed.

  In the sprinkling filter bed 100 shown in FIG. 1, the filter medium layer 30 is supported by the screen 20 at the lower end surface, but the sprinkling according to another embodiment to which the cleaning method of the sprinkling filter bed of the present invention can be applied. The filter bed may not have the screen 20, the column 21, the beam 22, and the like, and the lower end surface of the filter medium layer may coincide with or substantially coincide with the inner bottom surface of the water tank.

<Treatment of treated water>
Specifically, in the trickling filter 100, the treated water is sprayed onto the filter medium layer 30 through the sprinkler 50 with the treated water valve 52 and the valve 61 opened, thereby treating the treated water. More specifically, in the sprinkling filter bed 100, organic matter or the like in the water to be treated sprayed to the filter medium layer 30 through the water pipe 53 and the sprinkler 50 is treated with microorganisms (for example, BOD-oxidizing bacteria and ammonia-oxidizing bacteria that may exist in the biofilm formed on the surface of the filter medium 31 are aerobically biotreated. Further, the solid matter contained in the for-treatment water is captured by the filter medium layer 30. Then, the treated water obtained by treating the treated water with the filter medium layer 30 is discharged out of the sprinkling filter bed 100 through the pipe 60.

<Washing of filter media>
Here, if the treatment of the water to be treated is continued in the sprinkling filter bed 100, filter bed straw, scallop shells, etc. are generated, or microorganisms adhere excessively to the filter medium 31 and the biofilm becomes excessively thick. As a result, the water treatment performance may be degraded. Therefore, the filter medium 31 constituting the filter medium layer 30 is cleaned according to the watering filter bed cleaning method of the present invention. In cleaning the filter medium 31, in the sprinkling filter bed cleaning method of the present invention, first, a measurement step of measuring the amount of biofouling (Bm) on the filter medium is performed, and the amount of biofouling (Bm) obtained in the measurement step is measured. Based on the value, a cleaning process is performed by switching between agitation cleaning and immersion cleaning. In addition, the implementation frequency of a measurement process and a washing | cleaning process can be arbitrarily set according to a season, the attribute of treated water, etc.

[Measurement process]
In the measurement process, the amount of biological adhesion (Bm) to the filter medium is measured. The method for measuring the amount of biofouling (Bm) in the measurement process is not particularly limited. Examples of the measurement method include a method for detecting mass change of the filter medium layer 30 and a measurement method based on the porosity in the filter medium layer 30. Among these, from the viewpoint of simplicity and measurement accuracy, a measurement method based on the porosity is preferable.

  Here, conventionally, the cleaning process is generally performed at a timing determined using treated water quality or the like as an index, or every predetermined interval (for example, a predetermined number of operating days). However, the following inconveniences have been assumed in the methods that have been generally performed in the past. In other words, the degradation of treated water quality is caused only by the degradation of water treatment performance of the sprinkling filter bed due to the occurrence of filter bed spiders and shellfish and / or the thickening of the biofilm as described above. Rather than (i) a decrease in microbial activity due to a decrease in temperature of the filter medium layer, (ii) an outflow of attached microorganisms due to a long-term inflow of low concentration treated water, and (iii) an inflow of high concentration treated water It can also be caused by various factors such as overloading. Therefore, according to the conventional method, if the filter medium layer is stirred and washed when a decrease in the quality of the treated water is detected, the cause of the lowered quality of the treated water is as described in (i) to (iii) above. In addition, the amount of microorganisms retained in the filter medium layer is unnecessarily reduced, and there is a possibility that the quality of the treated water is further lowered. In addition, the number of operating days in which the water treatment performance of the filter medium layer is assumed to be deteriorated is determined in advance, and the cleaning process is performed every such operating days. In this method, good results can be obtained only under a special condition of flowing into the filter medium layer and the rate of adhesion of microorganisms to the filter medium layer being substantially constant. Therefore, in the actual sewage treatment in which various conditions such as the quality of the treated water, the water temperature, and the inflow amount can fluctuate, the agitation washing is performed even in a situation where the amount of microorganisms retained in the filter medium layer is insufficient. There is a fear. As a result, there is a possibility that the quality of treated water is further deteriorated. Thus, without directly measuring the amount of microorganisms or the like in the filter medium layer as in the past, so to speak, indirectly, the timing at which the amount of microorganisms in the filter medium layer may become inappropriate based on the quality of treated water or the number of operating days. However, it was difficult to maintain good water treatment performance by some methods.

  Therefore, as in the present invention, whether or not the amount of microorganisms adhering to the filter medium is sufficient by measuring the amount of biological adhesion (Bm) to the filter medium does not depend on an indirect indicator such as the quality of treated water. Can be grasped directly. Furthermore, in measuring the amount of biological adhesion (Bm) to the filter medium, according to the measurement method based on the mass or the porosity of the filter medium layer 30 as described above, the amount of microorganisms or the like in the filter medium layer 30 is directly and It can be measured with high accuracy. Especially, according to the measuring method based on the porosity of the filter medium layer 30, it is possible to easily and efficiently measure the amount of biological adhesion to the filter medium.

―Measurement of biofouling amount based on porosity―
The difference between the porosity (VRo) of the filter medium layer 30 and the predetermined porosity setting value (VRi) at the time of carrying out the measurement step can be used as the biological adhesion amount (Bm) in the filter medium layer 30. The predetermined porosity setting value (VRi) is calculated by using, for example, the void volume (V2) of the filter medium layer 30 before operation and the partial volume (V1) of the water tank 10 by the formula: V2 / V1 × 100 (%). Can be obtained as Note that the value of the predetermined porosity setting value (VRi) is not limited to the value calculated by “formula: V2 / V1 × 100 (%)”, and the operation of the water trickling filter 100 is continued. As necessary, it can be corrected appropriately.

  Further, the porosity (VRo) is obtained as an expression: V3 / V1 × 100 (%) using the filter medium layer void volume (V3) and the partial volume (V1) of the water tank 10 at the time of carrying out the measurement process. be able to. Hereinafter, with reference to FIG. 3, the measuring method at the time of measuring the porosity based on the amount of water will be described. The watering filter bed 100 shown in FIG. 3 is the same as the watering filter bed 100 shown in FIG.

The partial volume (V1) of the water tank 10 corresponds to the volume of the part including at least a part of the space filled with the filter medium 31 in the water tank 10. For example, the partial volume (V1) may be a partial volume of the water tank 10 corresponding to a position from the bottom surface to the upper end surface of the filter medium layer 30. In this case, the partial volume (V1) corresponds to the volume of the water tank 10 from the screen 20 corresponding to the bottom surface position of the filter medium layer 30 to the height of the filter medium layer upper end face 32. For example, the partial volume (V1) may be a partial volume of the water tank 10 including a portion corresponding to a part of the height of the filter medium layer 30. The partial volume (V1) can be calculated based on the calculation when the inner shape of the water tank 10 is a simple shape. Of course, in measuring the partial volume (V1), it is also possible to measure the accumulated inflow water amount in a predetermined section when water is introduced into the water tank 10 without filling the filter medium 31. In addition, it does not specifically limit as water used in this case, To-be-processed water, reclaimed water, middle water, river water, tap water, industrial water, etc. can be used. Further, the “predetermined section” is not particularly limited as long as at least a part of the filter medium layer 30 is included, and may be any section. For example, the predetermined section that is “at least a part” of the filter medium layer 30 is a section having one end at least one of the upper side of the lower end surface of the filter medium layer 30 and the lower side of the upper end surface of the filter medium layer 30. obtain. In particular, as shown in FIG. 3, when the height from the screen 20 (that is, the lower end surface of the filter medium layer 30) to the upper end surface 32 of the filter medium layer is H, H / 40 or more from the lower end surface of the filter medium layer 30. One measurement start height (Hs) included in the height range of H / 10 or less and one measurement end height (He) included in the range of H / 40 or more and H / 10 or less from the filter medium layer upper end surface 32 It is preferable that it is the area h divided by these. In addition, the scale in FIG. 3 and the positional relationship between each component are not limited to this. By setting the upper and lower limits of the “predetermined section” so as not to include the vicinity of the bottom surface and the vicinity of the upper end surface of the filter medium layer 30, it is caused by deterioration of the filter medium 31 due to repeated use, etc., and the weight of the filter medium 31 itself. It is because it can suppress effectively that the precision of the various measured values obtained through a measurement process falls because compaction etc. generate | occur | produce. In particular, by not including the region in the vicinity of the lower end surface of the filter medium layer 30 in the “predetermined section”, it is possible to reduce the influence of the change in the void volume due to consolidation or the like on the measurement value. In addition, by not including the region near the upper end surface 32 of the filter medium layer 30 in the “predetermined section”, an error may occur in the measured value due to a change in the height of the filter medium layer 30 due to compaction and deterioration of the filter medium 31. Can be reduced. Furthermore, the time required for the measurement process can be shortened by setting “at least a part” instead of “all” of the filter medium layer 30 as the calculation target region of the cumulative inflow water amount.

A method for measuring the cumulative inflow amount of water from the measurement start height (Hs) to the measurement end height (He) using the water level meter 71 is, for example, as follows. As described above, the flow meter 51 constantly measures the flow rate of the supply water. Therefore, the measurement start height (Hs) is obtained by obtaining the integrated flow rate from the time when the water level detected by the water level gauge 71 becomes Hs to the time when the water level detected by the water level gauge 71 becomes He. ) To the measurement end height (He) as a “predetermined section”, the cumulative inflow water amount (corresponding to a partial volume (V1) of the water tank 10) can be obtained. As described above, from the viewpoint of obtaining the partial volume (V1) of the water tank 10, when the internal shape of the water tank 10 is a simple shape such as a cylindrical shape, the height (He-Hs) Of course, it is possible to obtain the partial volume (V1) of the water tank 10 by multiplying the cross-sectional area of the water tank 10.

Further, the void volume (V2) of the filter medium layer 30 before operation is such that a new filter medium is filled in the water tank 10 and the valve 61 is closed to allow water to flow into the water tank 10 and to the predetermined section of the filter medium layer 30. It can be measured as the accumulated inflow of water. The void volume (V2) represents the total volume of voids in the filter medium layer 30 in a state where no biofilm is attached to the filter medium 31. The method for measuring the void volume (V2) based on the accumulated inflow water amount is the same as that for obtaining the partial volume (V1) of the water tank 10.

  The filter medium layer void volume (V3) at the time of carrying out the measurement step is such that when the measurement step is carried out after the operation of the sprinkling filter bed 100 is started, the valve 61 is closed and the cleaning liquid is caused to flow into the water tank 10. It can be measured as the accumulated inflow water amount to a predetermined section of the layer 30. In other words, the filter medium layer void volume (V3) represents the entire volume of the voids of the filter medium layer 30 in a state where the biofilm is attached to the filter medium 31. The cleaning liquid is not particularly limited as long as it is a liquid, and water to be treated, reclaimed water, middle water, river water, tap water, industrial water, chemical liquid, and the like can be used. Especially, it is preferable to use to-be-processed water as a washing | cleaning liquid from a viewpoint of cost reduction and the simplification of the structure of a trickling filter bed. In addition, the measuring method of the filter medium layer space | gap part volume (V3) based on accumulated inflow water amount is the same as when calculating | requiring the partial volume (V1) of the water tank 10. FIG.

These partial volume (V1) of the water tank 10 and the void volume (V2) of the filter medium layer 30 before operation.
The predetermined porosity setting value (VRi) calculated in accordance with the formula: V2 / V1 × 100 (%) is a void in the filter medium layer 30 in a state where no biofilm is attached to the filter medium 31. The ratio (%) is shown. Moreover, based on the partial volume (V1) of the water tank 10 and the filter medium layer void volume (V3) at the time of carrying out the measurement step, the porosity (VRo) calculated according to the formula: V3 / V1 × 100 (%) These show the ratio (%) of the space | gap in the filter medium layer 30 in the state in which the biofilm has adhered with respect to the filter medium 31. FIG. Therefore, by calculating the difference between the porosity (VRo) and the predetermined porosity setting value (VRi), it is possible to determine how much the porosity in the filter medium layer 30 is reduced by the biofilm attached to the filter medium 31. I can grasp it. This means that the amount of the biofilm and the like is increased by the amount of the decreased gap, and therefore the value of (VRo−VRi) can be said to be an index that directly represents the state of the filter medium layer 30. In addition, the value of (VRo−VRi) includes not only the thickening of the biofilm but also the solid content in the water to be treated captured by the filter medium layer 30, and the amount of filter bed cake generated in the filter medium layer 30. The effects of larvae and scallops can also be reflected.

  Here, in the above description, the measurement method using the porosity, which is a preferable method for obtaining the biological adhesion amount (Bm), has been specifically described. Separately from this, when measuring the amount of biological adhesion (Bm) based on the mass change of the filter medium layer 30, the amount of biological adhesion is determined from the mass (Mo) of at least a part of the filter medium layer 30 at the time of measurement. Can be calculated as a difference value obtained by subtracting the mass set value (Mi). For example, the predetermined mass setting value (Mi) can be calculated by multiplying the number of filter media included when calculating the mass (Mo) by the mass of the new filter media.

[Washing process]
In the washing step, the filter medium 31 is washed. More specifically, in the washing step, when the biological adhesion amount (Bm) obtained in the above-described measurement step exceeds a predetermined washing selected biological adhesion amount (Bw), the filter medium 31 is “stir washed” When the adhesion amount (Bm) is equal to or less than the predetermined washing selected organism adhesion amount (Bw), the filter medium 31 is “immersed and washed”. Here, the “cleaning-selected biological adhesion amount (Bw)” is a value serving as a threshold when selecting a cleaning method in the cleaning process. Hereinafter, a cleaning operation in the cleaning process and a method of setting the cleaning selected biological attachment amount (Bw) will be described in detail. For example, in the measurement step described above, when the biological adhesion amount (Bm) is measured based on the accumulated inflow water amount of the wash water, the operation for flowing the wash water in the “washing operation” described below is performed. In the measurement process, the operation can be substituted by an operation of flowing the washing water into the water tank 10. That is, in the measurement process, when the amount of biological adhesion (Bm, that is, VRo-VRi) is obtained by the measurement method using the porosity, the washing water used in the measurement process is directly used in the washing process. Can be used. Such an embodiment is very advantageous and rational from the viewpoint of the efficiency of water treatment.

―Cleaning operation―
--Immersion cleaning First, in the case of immersing and cleaning the sprinkling filter bed 100, after closing the valve 61 provided in the pipe 60, the water to be treated as a cleaning liquid is put into the water tank 10 using the sprinkler 50. Let it flow to a height above 30. Next, watering of the water to be treated from the watering machine 50 is stopped, and the filter medium layer 30 is immersed for a predetermined time (for example, 12 hours). Then, after the predetermined time has elapsed, the valve 61 is opened to drain the water to be treated stored in the water tank 10, and when the drainage is completed, watering from the water sprinkler 50 is started and the operation of the watering filter bed 100 is resumed. To do. As described above, the immersion cleaning is a cleaning method in which water is filled in the water tank 10 and then drained after being held for a certain period of time, and has an effect of extermination of eggs, larvae, shellfish eggs, etc., but does not perturb the filter medium 31. This is a weak cleaning method with little peeling of the biofilm from the filter medium 31.

—Agitating and Washing Next, a case where the watering filter bed 100 is agitated and washed will be described with reference to FIG. FIG. 4 shows a state where the watering filter bed 100 is stirred and washed by air aeration. After closing the valve 61 provided in the pipe 60, the water to be treated as the cleaning liquid is caused to flow into the water tank 10 using the sprinkler 50 to a height exceeding the filter medium layer 30, and then the water to be treated from the water sprinkler 50 is used. Stop watering. Subsequently, air is ejected from the aeration apparatus 40 to perform aeration, and the filter medium 31 is caused to flow by the levitation force of the air. In this way, the agitation washing removes a part of the biofilm that has become thicker by adhering to the filter medium, the sludge accumulated in the filter medium layer 30, solids, cocoon eggs, moth larvae, shellfish, and eggs thereof. It is a powerful cleaning method that can.

In FIG. 4, a mode in which the filter medium 31 is stirred using the aeration apparatus 40 is illustrated, but the stirring of the filter medium 31 immersed in the cleaning liquid is not particularly limited, and a physical stirring device such as a stirrer is used. It may be performed by generating a water flow in the water tank. However, from the viewpoint of simplifying the structure of the sprinkling filter bed 100 and preventing the filter medium 31 from being damaged, the filter medium 31 is preferably agitated by aeration, and is installed below the filter medium layer 30 as shown in FIG. More preferably, the aeration apparatus 40 is used to aerate a gas such as air and cause the filter medium 31 and the cleaning liquid to flow. Aeration amount when stirring the filter medium by aeration is preferably 0.25 m ³ / m is ² · min or more 1.5 m ³ / m or less ² · min, 0.25 m ³ / m ² · min or more 0. More preferably, it is 5 m ³ / m ² · min or less.

―Washing amount of selected organisms (Bw) ―
The washing selected biological adhesion amount (Bw) is a very important threshold for operating the water trickling filter 100 while maintaining the water treatment performance of the water trickling filter 100 well. For example, in the case of calculating the biological attachment “amount” based on the porosity in the filter medium layer 30, the cleaning-selected biological adhesion amount (Bw) is “the biological attachment amount calculated based on the porosity. It can be determined based on the relationship between the “rate” and the water treatment performance of the trickling filter. In addition, the “bioadhesion rate” in the description with reference to FIGS. 5 and 6 is the above-mentioned “porosity (VRo): porosity and porosity set value (VRi) of the filter medium layer 30 at the time of the measurement step: before operation. This corresponds to “the difference from the porosity of the filter medium layer 30”. FIG. 5 is a graph showing the relationship between the biofouling rate and the amount of soluble BOD (Biochemical oxygen demand) removed in a water trickling filter having a water tank cross-sectional area of 56.25 m ² and a filter medium filling height of 2.5 m. These are the graphs which show the relationship between the biofouling rate and the amount of ammonia nitrogen removal in the sprinkling filter of the same shape. In addition, the graph shown to FIGS. 5-6 is the measurement data of the processing performance of the trickling filter which the present inventors acquired. The conditions for obtaining the measured data were a water tank cross-sectional area of 56.25 m ² and a filter medium filling height of 2.5 m, water to be treated was city sewage, and the amount of treated water was 1100 m ³ / day.

  First, a description will be given with reference to FIG. As is clear from FIG. 5, the amount of soluble BOD removed increases with an increase in the bioadhesion rate (%), the bioadhesion rate reaches its maximum at 10% to 20%, and the solubility increases when the bioadhesion rate further increases. BOD removal amount tends to decrease.

  Moreover, from FIG. 6, the amount of ammonia nitrogen removal increases with an increase in the biofouling rate, the biofouling rate becomes maximum at 10% to 20%, and further shows a tendency to decrease as the biofouling rate increases. I understand.

  From these measured data shown in FIGS. 5 to 6, the treatment performance of the sprinkling filter bed shown as soluble BOD removal amount or ammonia nitrogen removal amount is good when the biofouling rate is 5% to 25%, In particular, it can be said that the performance is high in the range of 10% to 20%, and that the processing performance is deteriorated when it is less than 5% or more than 25%.

  It is assumed that the reason why the processing performance changes in this way is as follows. First, when the biofouling rate is less than 5%, the amount of microorganisms retained in the filter medium layer 30 is insufficient with respect to the amount of pollutant contained in the water to be treated, and the treatment performance is low. Conceivable. On the other hand, when the bioadhesion rate is more than 25%, the biofilm adhered to the filter medium packed in the filter medium layer is excessively thick, and an excessive amount of sludge accumulates in the voids of the filter medium. As a result, sludge decay occurs, and as a result, elution of organic substances, ammonia and the like from the decayed sludge occurs, and it is considered that the treatment performance of the sprinkling filter is lowered.

  Therefore, it is important to maintain the biofouling rate in the range of 10% to 20% in the operation of the trickling filter that has obtained the actual measurement data shown in FIGS. It is thought that it is preferable to maintain the above. And the value of the washing | cleaning selection biofouling amount (Bw) which should be set in order to maintain a biofouling rate in the range of 10%-20% may be 10% of a biofouling rate. That is, the value of 10% of the biofouling rate may be the amount of microorganisms that is desired to be maintained at a minimum in the trickling filter that has obtained the actual measurement data shown in FIGS. Hereinafter, the selection of the cleaning method in the cleaning process when the biological adhesion rate of 10% is set as the cleaning selection biological adhesion amount (Bw) will be specifically described.

-Selection of cleaning method based on the amount of attached biological organisms (Bw)-
Selection of a cleaning method using the bioadhesion rate obtained based on the porosity of the filter medium layer will be described with reference to FIG. FIG. 7 is a graph showing the relationship between the biofouling rate and the soluble BOD removal amount previously shown in FIG. As is clear from FIG. 7, the cleaning to be performed in the cleaning process is switched between the immersion cleaning and the agitation cleaning with the biofouling rate of 10% as a boundary.

  In the case shown in FIG. 7, when the biofouling amount (Bm) obtained in the measurement step is less than or equal to the washing selected biofouling amount (Bw), that is, the filter medium at the time of performing the measurement step measured using the porosity. When the difference between the layer porosity (VRo) and the predetermined porosity setting value (VRi) is 10% or less, dip cleaning with less biological separation from the filter medium is selected. In addition, when the amount of biofouling (Bm) obtained in the measurement step is greater than the amount of selected biofouling (Bw), that is, the porosity of the filter medium layer at the time of the measurement step measured using the porosity ( When the difference between VRo) and the predetermined porosity setting value (VRi) is more than 10%, the agitation cleaning is selected so that biological separation from the filter medium is large and sludge can be discharged. Note that these determination and selection operations can be automatically performed by, for example, a computer equipped with a central processing unit and the like provided in the monitoring control device 90 in the case of the trickling filter 100 shown in FIG. . Of course, the operator (person) can determine the magnitude relationship between the biological attachment amount (Bm) and the cleaning-selected biological attachment amount (Bw), and manually switch the cleaning method. In particular, according to the method for cleaning a trickling filter of the present invention, a simple comparison between a “thickness of selected biofouling (Bw)” that is one threshold value and a biofouling amount (Bm) obtained in the measurement step, The cleaning method to be performed at that time can be uniquely determined. Therefore, it is possible to always optimize the amount of microorganisms retained in the sprinkling filter bed regardless of the operator's experience and without the need for human judgment. For this reason, the maintenance of the sprinkling filter bed becomes easy.

  In addition, the specific value of the washing selected biological attachment amount (Bw) is the watering load, the target treated water quality, the treated water quality, the treated water, etc. in the trickling filter bed to which the washing method of the trickling filter according to the present invention is applied The temperature can be appropriately changed based on various parameters that can affect the ease of accumulation of sludge in the filter medium layer, such as the BOD of the water to be treated. In addition, for example, it is of course possible to change the specific numerical value of the washing selected organism adhesion amount (Bw) according to the season. By setting the appropriate value for the amount of selected organisms to be washed (Bw), for example, the period required for the eggs of the pupa to become larvae or adults, and / or until the larvae of Sakimakai become adults. A cleaning step according to an appropriate cleaning method can be carried out in a shorter period than the required period, and the occurrence of filter bed larvae, scallops, and the like from the sprinkling filter bed can be effectively suppressed.

  Further, in the washing process, the amount of biological adhesion (Bm) measured in the measurement process (for example, the porosity (VRo) of the filter medium layer 30 at the time of the measurement process measured using the porosity as described above and a predetermined value) When the porosity setting value (VRi) is more than the washing selected biological attachment amount (Bw), the stirring washing based on the difference (Bd = Bm−Bw) from the washing selected biological attachment amount (Bw) It is preferable to adjust the cleaning strength. FIG. 8 shows the relationship between Bm, Bw, and Bd superimposed on the graph showing the relationship between the same bioadhesion rate and soluble BOD removal amount as in FIG. In FIG. 8, the various biological attachment amounts and the difference mean biological attachment amounts based on the porosity.

  Here, when the difference (Bm) − (Bw) = (Bd) between the biological adhesion amount (Bm) measured in the measurement process and the washing selected biological adhesion amount (Bw) is calculated, the difference (Bd) is large. It can be determined that the amount of biofilm and sludge adhering to the filter medium constituting the filter medium layer is large, and the amount of microorganisms retained in the filter medium layer is large. Therefore, when the value of the difference (Bd) is large, it is preferable to perform a powerful stirring process and peel off the biological film and sludge from the filter medium with a strong force, compared to the case where the value of Bd is small. On the other hand, when the value of the difference (Bd) is small, the amount of microorganisms retained in the filter medium layer is relatively small, and it can be determined that it is only slightly larger than the washing selected organism adhesion amount (Bw). It is preferable to perform the agitation treatment to remove the biofilm and the sludge from the filter medium with a gentle force.

  More specifically, in the case of agitation cleaning by typical air aeration, the cleaning strength is defined by the product (Qt) of the air flow rate (Q) and the aeration time (t), and the biofouling obtained by measurement and calculation It is preferable to adjust (Qt) according to the value of the amount difference (Bd). By changing (Qt), it is possible to adjust the amount of sludge to be peeled off by stirring and washing, and to adjust the amount of microorganisms retained in the sprinkling filter bed to an appropriate range.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to the following Example at all. The trickling filter used in the examples had the same configuration as the trickling filter 100 described with reference to FIG. Moreover, the amount of biofouling was measured as the biofouling rate (%) based on the porosity as described above.

Example 1
Treatment was performed by flowing municipal sewage at a flow rate of 1100 m ³ / day into a sprinkling filter bed having a water tank cross-sectional area of 56.25 m ² and a filter medium filling height of 2.5 m. The average specific gravity of the unused filter medium was 1.03 (100 number average value). The washing selected biofouling amount (Bw) was a biofouling rate based on the porosity and was set to 10%. The aeration intensity when the filter medium was stirred and washed in the washing step was constant at 0.25 m ³ / m ² · min. Further, in the cleaning process, according to the following criteria, switching between stirring cleaning and immersion cleaning is performed according to the value of VRd: (biological adhesion rate (%)-10% at the time of performing the measuring process), and stirring cleaning is further performed. When performing, the aeration time was automatically changed.
VRd ≧ 15%: aeration 5 minutes 10% ≦ VRd <15%: aeration 3 minutes 5% ≦ VRd <10%: aeration 2 minutes 0% ≦ VRd <5%: aeration 1 minute VRd <0%: immersion cleaning (aeration 0 minutes)

  The implementation period of Example 1 was a period when the organic matter concentration of sewage was relatively high. It was 12.3 mg / L when BOD of the treated water obtained by processing with a trickling filter was measured. Therefore, the measurement process was performed immediately after the BOD was measured, and the bioadhesion rate, which is the amount of bioadhesion based on the porosity, of the filter medium layer of the watering filter bed was 27.3%. Then, the difference between the biofouling rate at the time when the measurement process is performed and the biofouling rate of 10% as the washing selected biofouling amount (Bw) is 17.3%. Therefore, according to the above criteria, the filter medium was stirred and washed with an aeration time of 5 minutes. One week after the completion of the washing step, the BOD of the treated water was measured and found to be 8 mg / L. Therefore, in the said washing | cleaning process, it was confirmed that the water treatment performance of the sprinkling filter bed improved by performing the stirring washing | cleaning which made the aeration time 5 minutes. Moreover, it was confirmed that by performing the above washing step, the numbers of filter bed cocoons and scallop shells were clearly smaller than before washing, and the growth of filter bed cocoons and scallop shells was suppressed.

(Example 2)
Using the same sprinkling filter bed as in Example 1, sewage treatment was performed according to the same criteria as in Example 1.
The implementation period of Example 2 was a period when the organic matter concentration of sewage was relatively low. It was 9.8 mg / L when BOD of the treated water obtained by processing with a trickling filter was measured. Moreover, when the density | concentration of ammonia nitrogen was measured about treated water, it was 6.5 mg / L and it was a comparatively low density | concentration. And immediately after the time of measuring the concentrations of BOD and ammonia nitrogen, the bioadhesion rate, which is the bioadhesion amount based on the porosity, is measured at 8.8% for the filter medium layer of the watering filter bed. there were. Then, the difference between the biofouling rate at the time when the measurement step is performed and the biofouling rate of 10% as the washing selected biofouling amount (Bw) is −1.2%. Therefore, in accordance with the above criteria, immersion cleaning was selected as the cleaning method, and aeration was not performed. As a result, separation and outflow of microorganisms adhering to the filter medium are suppressed, the quality of the treated water gradually improves after washing, the BOD of the treated water is 7.4 mg / L after one week, and the ammonia nitrogen concentration of the treated water is 4 Reduced to 5 mg / L. Moreover, it was confirmed that by performing the above washing step, the numbers of filter bed cocoons and scallop shells were clearly smaller than before washing, and the growth of filter bed cocoons and scallop shells was suppressed.

  According to the present invention, the filter medium is washed by an appropriate method in accordance with the amount of biofouling on the filter medium, thereby suppressing the generation of larvae and scallops from the sprinkling filter bed, and the watering filter bed. Can effectively restore the water treatment capacity.

DESCRIPTION OF SYMBOLS 10 Water tank 20 Screen 21 Column 22 Beam 30 Filter medium layer 31 Filter medium 32 Filter medium layer upper end surface 40 Aeration apparatus 50 Sprinkler 51 Flow meter 52 Processed water valve 53 Processed water pipe 60 Pipe 61 Valve 70 Connection pipe 71 Water level gauge 80 Blower 81 Air piping for stirring 90 Monitoring and control device 100 Sprinkling filter

Claims (5)

A watering filter bed cleaning method having a filter medium layer comprising a plurality of filter media in a water tank,
A measurement step of measuring the amount of biological adhesion (Bm) to the filter medium;
A washing step of washing the filter medium,
In the washing step, when the biofouling amount (Bm) exceeds a predetermined washing selected biofouling amount (Bw), the filter medium is stirred and washed, and the biofouling amount (Bm) is the washing selected biofouling amount. (Bw) If it is below, the filter medium is immersed and washed,
How to wash the sprinkling filter. In measuring the biological adhesion amount (Bm) in the measurement step, the porosity (VRo) of the filter medium layer is measured, and a difference from a predetermined porosity setting value (VRi) is obtained.
The watering filter bed washing method according to claim 1.   3. The measurement according to claim 2, wherein, in the measurement step, the porosity (VRo) is measured based on a cumulative inflow water amount to a predetermined section of the filter medium layer when a cleaning liquid is caused to flow into the filter medium layer. How to clean the sprinkling filter floor.   The predetermined section of the filter medium layer is one measurement start height included in a height range from H / 40 to H / 10 from the lower end surface of the filter medium layer, where H is the height of the filter medium layer. The sprinkling filter bed according to claim 3, which is partitioned by (Hs) and one measurement end height (He) included in a range of H / 40 or more and H / 10 or less from the upper end surface of the filter medium layer. Cleaning method. In the washing step,
When the biofouling amount (Bm) exceeds the washing selected biofouling amount (Bw), the washing at the time of the agitation washing based on the difference (Bd = Bm−Bw) from the washing selected biofouling amount (Bw) Including adjusting the intensity,
The washing method of the trickling filter bed in any one of Claims 1-4.

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